Lift of an airborne vehicle is ordinarily achieved by movement of air relative to an airfoil. Such relative movement is achieved in a conventional fixed wing aircraft by movement of the aircraft through the air mass. In a helicopter relative movement between an airfoil and the air mass is achieved by movement of the airfoil relative to the vehicle. While airborne vehicles that rely only on thrust for ascent are known, movement in a horizontal plane has not heretofore been achieved by a change in the center of gravity of the vehicle relative to vertical thrust of the engine.